4. Graph object thread safety

Graph objects (cudaGraph_t, CUgraph) are not internally synchronized and must not be accessed concurrently from multiple threads. API calls accessing the same graph object must be serialized externally.

Note that this includes APIs which may appear to be read-only, such as cudaGraphClone() (cuGraphClone()) and cudaGraphInstantiate() (cuGraphInstantiate()). No API or pair of APIs is guaranteed to be safe to call on the same graph object from two different threads without serialization.